The present invention relates to means for indicating the extent of fill of containers in a container handling apparatus, and more particularly to means for indicating the extent of fill of containers traveling on individual container stations of the conveyor in comparison with a preset selected fill extent.
Accuracy in filling and sensing the extent of fill in containers is a critical aspect of most container filling operations because intentional, but expensive, overfilling must be programmed into the operation to assure that substantially all of the containers are filled to a required minimum. Therefore, accurate and fast sensing of the extent of fill is desirable to facilitate detection of fill variations so that, for example, compensations can be made in the filling of the container being checked or in filling subsequent containers.
There is also an increasing demand for faster production in filling operations to reduce cost and increase efficiency, for which purpose it is almost a necessity that the extent of filling be sensed as the containers are traveling, rather than stopped in an otherwise continuously moving operation. Thus, it is desirable that the sensing occur on traveling container stations, but this presents problems of accuracy and reliability of results where the controls for the sensing must, as in the case of sophisticated and potentially accurate electronic controls, have components on the traveling station connected to non-travelling components or where there are a number of traveling sensing stations that must be related.
For example, in apparatus for filling containers as they travel sequentially on container stations of an endless conveyor, such as in a rotary filling machine, it would be advantageous to be able to sense the extent of fill accurately during the filling operation and compare the sensed extent to determine when to stop filling. This could be done with mechanical, hydraulic or pneumatic controls, but with a substantial and undesirable sacrifice in speed due to the relative slow action of such systems, but electrical systems, while faster acting, have not been able to be used to their accuracy, fast response and versatility potential in systems where the sensing is occurring at a sequence of traveling container stations.